Apparatus for manufacturing coil spring

ABSTRACT

An apparatus for manufacturing a coil spring. In the apparatus, a body is provided and a pair of machining units are disposed on the body to oppose each other at one end thereof. In each of the machining units, a mandrel is disposed in an upper central part of the body. The mandrel is rotatably configured to wind a coil spring material around an outer circumference thereof. A first motor is disposed at the other end of the machining unit to provide a driving force for rotating the mandrel. Also, a guide roller part is disposed movable along a length direction of the mandrel to guide the coil spring material to be wound around the mandrel. Two coil spring materials produced from a furnace are wound around the mandrels, respectively to produce two coil springs through one process.

TECHNICAL FIELD

The present invention relates to an apparatus for manufacturing a coilspring, more particularly, in which two coil spring materials producedfrom a furnace are transported to two mandrels spaced apart at a shortdistance to be wound therearound, respectively, to produce two coilsprings through one process.

BACKGROUND ART

In general, a coil spring has been manually manufactured by a skilledhand. However, for this purpose, only primitive equipment such as ashaft sealing or an apparatus for winding a heat-treated coil has beenemployed, thereby resulting in low productivity and non-uniformproducts.

Efforts have been unceasingly under way to solve problems associatedwith the conventional manufacturing method of the coil spring. Againstthis technologic backdrop, there has been a development of an apparatusfor manufacturing the coil spring by winding a coil spring materialproduced from a furnace around a motor-rotated mandrel.

As shown in FIG. 1, the apparatus for manufacturing the coil spring hasa motor 3 installed at one end of a mandrel 4. A driving shaft of themotor 3 rotates the mandrel 4 through a gear 6 inside a gear box 5.

Also, a chuck 7 is formed at the one end of the mandrel 4 to press theone end of the coil spring material 2 toward the mandrel 4 for fixing. Adriving means 8 is disposed at the one end of the mandrel 4 to move thechuck 7 vertically with respect to a length direction of the mandrel 4.

The driving means 8 includes a rotating cylinder 8 a and a rotatingshaft 8 b rotating by the rotating cylinder 8 a. Here, the rotatingshaft 8 b is disposed rotatable about the gear box installed in a body.

That is, in the conventional apparatus for manufacturing the coilspring, the motor 3 and the gear 6 are disposed at the one end of themandrel 4 and the rotating cylinder 8 a and the rotating shaft 8 b arealso disposed at the one end of the mandrel 4.

The apparatus for manufacturing the coil spring as configured above hasbeen improved partially in terms of a manufacturing method over themanual production of the coil spring. But the apparatus as justdescribed also bears limitations due to inability to produce a greatnumber of coil springs. That is, the apparatus for manufacturing thecoil spring is configured such that only one coil spring is producedwith a coil spring material 2 produced from a furnace, therebydemonstrating ineffective productivity.

DISCLOSURE OF INVENTION Technical Problem

The present invention has been made to solve the foregoing problems ofthe prior art and therefore an aspect of the present invention is toprovide an apparatus for manufacturing a coil spring in which two coilspring materials produced from a furnace are transported to two mandrelsspaced apart from each other at a short distance to be woundtherearound, respectively to produce two coil springs through a process.

Technical Solution

According to an aspect of the invention, the invention provides anapparatus for manufacturing a coil spring. The apparatus includes abody; a pair of machining units disposed on the body to oppose eachother at one end thereof, wherein each of the machining units includes amandrel disposed in an upper central part of the body, the mandrelrotatably configured to wind a coil spring material around an outercircumference thereof; a first motor disposed at the other end of themachining unit to provide a driving force for rotating the mandrel; anda guide roller part disposed movable along a length direction of themandrel to guide the coil spring material to be wound around themandrel, wherein two coil spring materials produced from a furnace arewound around the mandrels, respectively to produce two coil springsthrough one process.

Each of the machining units further includes a chuck configuredvertically movable and disposed at one end of the mandrel to fix one endof the coil spring material to the one end of the mandrel; and a firstcylinder disposed at the one end of the mandrel perpendicular to alength direction of the mandrel to provide a driving force for movingthe chuck vertically with respect to the length direction of themandrel.

Preferably, each of the guide roller parts includes a guide roller forpressing and guiding the coil spring material wound around the mandreltoward the mandrel; a second cylinder disposed at an outer circumferenceof the mandrel to oppose each other, thereby moving the guide rollervertically and; a transport part having a screw shaft rotating by asecond motor to transport the guide roller along the length direction ofthe mandrel and a guide shaft for guiding the guide roller.

Moreover, preferably, the guide roller part further includes a thirdcylinder configured to reciprocally move the guide roller along theguide shaft to adjust a lead angle of the coil spring material while theguide roller moves along the screw shaft.

Preferably, a pair of the guide roller part is disposed at both sides ofthe mandrel to selectively produce a left- or right-handed coil spring.

In the apparatus for manufacturing the coil spring, the body isconfigured as an upper body and a lower body with respect to hingesformed respectively below the mandrels, wherein the mandrels, the firstmotors, and the guide roller parts are disposed in the upper body, theapparatus further including third motors disposed in the lower body torotate the upper body around the hinges.

Also, preferably, each of the machining units further includes a tangentroller spaced apart at a predetermined distance from the outercircumference of the mandrel to separate the other end of the coilspring material from the mandrels, thereby guiding the other end of themoving coil spring material.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a view illustrating a conventional apparatus for manufacturinga coil spring;

FIG. 2 is a schematic view illustrating two mandrels of an apparatus formanufacturing a coil spring to which coil spring materials produced froma furnace are transported according to a preferred embodiment;

FIG. 3 is a front view illustrating an apparatus for manufacturing acoil spring according to a preferred embodiment of the invention;

FIG. 4 is a front configuration view illustrating a front end of amandrel in the apparatus for manufacturing the coil spring of FIG. 3;

FIG. 5 is a plan view illustrating the apparatus for manufacturing thecoil spring of FIG. 3;

FIG. 6 is a side view illustrating a guide roller part of the apparatusfor manufacturing the coil spring of FIG. 5; and

FIG. 7 is a plan view illustrating the guide roller part of FIG. 6;

BEST MODE FOR CARRYING OUT THE INVENTION

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

FIG. 2 is a schematic view illustrating two mandrels of an apparatus formanufacturing a coil spring to which coil spring materials produced froma furnace are transported according to a preferred embodiment. FIG. 3 isa front view illustrating an apparatus for manufacturing a coil springaccording to a preferred embodiment of the invention. FIG. 4 is a frontconfiguration view illustrating a front end of the apparatus formanufacturing the coil spring of FIG. 3.

With reference to the drawings, the apparatus for manufacturing the coilspring of the invention can produce a coil spring from respective twomandrels 40 at one time. The apparatus includes a body 20 and a pair ofmachining units disposed on the body 20 to oppose each other at one endthereof. Each of the machining units includes a mandrel 40 disposed inthe body 20, a first motor 50 and a guide roller part 60.

The two mandrels 40 are disposed in an upper central part of the body tooppose each other at one end thereof. That is, the mandrels 40 aredisposed in an upper central part of the body 20 to be spaced apart fromeach other at a short distance.

The mandrels 40 are positioned such that a coil spring is produced fromthe respective mandrels 40 at one time. That is, according to theinvention, to produce two coil springs at one time, the two mandrels 40are installed within a close proximity so that two coil spring materials2 produced from a furnace 1 are transported to the mandrels 40,respectively through a door of the furnace 1.

Each of the mandrels 40 has one end disposed in a mandrel fixing part 42and the other end disposed in a mandrel gear 48. In this configuration,the mandrel 40 has the one end provided with a square fixing pillar 40 aat one side thereof to be inserted into an angled fixing protrusion 42 aformed in the mandrel fixing part 42, and the other end engagingly fixedto the mandrel gear 48. This prevents the mandrel 40 from idling withrespect to the mandrel fixing part 42 and the mandrel gear 48.

Here, the mandrel 40 is rotatably configured to wind each of the coilspring materials 2 around an outer circumference thereof. The firstmotor 50 is disposed at the other end of the machining unit to provide adriving force for rotating the mandrel.

As just described, to rotate the mandrel 40 by the first motor 50, thefirst motor 50 is started and a ball spline shaft 54 connected to thefirst motor 50 and a timing belt 52 is rotated. Then the rotating ballspline shaft 54 rotates the mandrel gear 48 meshing with the ball splineshaft 54, eventually rotating the mandrel 40 having the other endengagingly attached to the mandrel gear 48.

Also, the mandrel gear 48 engagingly attached to the other end of themandrel 40 is installed in the mandrel gear box 49. The mandrel gear box49 is disposed movable on a linear rail 49 b installed in the body 20 byvirtue of an air cylinder 49 a.

As just described, the mandrel gear box 49 is movably configured so thatthe mandrel 40 engagingly attached to the mandrel gear 48 of the mandrelgear box 49 becomes movable. Accordingly, with the coil spring completedin the mandrel 40, the mandrel 40 is moved to be spaced apart from themandrel fixing part 42, thereby detaching the coil spring from themandrel 40.

That is, when wound around the outer circumference of the mandrel 40into the coil spring, the mandrel gear box 49 is moved by the aircylinder 49 a, separating the mandrel 40 from the mandrel fixing part42. Then, the coil spring material 2 is moved to the other end of themandrel 40. In this fashion, the mandrel 40 is moved and the coil springhaving the one end fixed to the mandrel 40 by the chuck 90 is disengagedfrom the mandrel 40. Then, the coil spring disengaged from the mandrel40 drops off to be collected.

Here, to detach the mandrel 40 from the mandrel fixing part 42, thesquare fixing pillar 40 a formed at the one end side portion of themandrel 40 is disengaged from the angled fixing protrusion 42 a of themandrel fixing part 42.

Also, the mandrel 40 can be replaced depending on the type and diametersize of the coil spring to be manufactured.

Meanwhile, as shown in FIG. 4, each of the machining units furtherincludes a chuck 90 and a first cylinder 92. The chuck 90 is configuredvertically movable and disposed at one end of the mandrel to fix one endof the coil spring material 2 to the one end of the mandrel 40. Thefirst cylinder 92 provides a driving force for moving the chuck 90vertically with respect to the length direction of the mandrel.

The chuck 90 is disposed vertically movable on the mandrel fixing part42 fixed to the one end of the mandrel 40. The chuck 90 presses the oneend of the coil spring 2 against the mandrel 40 with a predeterminedpower or more, thereby fastening the one end of the coil spring material2 to the mandrel 40.

The first cylinder 92 providing a driving force for vertically movingthe chuck 90 is disposed in the mandrel fixing part 42 installed at theone end of the mandrel 40, perpendicular to a length direction of themandrel 40.

In addition, the mandrel fixing part 42 fastened to the one end of themandrel rotating by the first motor 50 is rotated along with the mandrel40. The rotating mandrel fixing part 42 is joined to the body 20 by arotary joint 44.

The body 20 has a stopper cylinder 46 configured to stop the mandrelfixing part 42, which is connected to the mandrel 40 to rotate, at acertain position.

That is, the stopper cylinder 46 stops the mandrel fixing part 42 at acertain position so that in a case where the mandrel 40 has the one enddetached from the mandrel fixing part 42 and then re-joined to themandrel fixing part 42, the square fixing pillar 40 a at the one end ofthe mandrel 40 is inserted into the angled fixing protrusion 42 a of themandrel fixing part 42.

In the apparatus for manufacturing the coil spring as just configured,each of the machining units includes the mandrel 40 and the first motor50 disposed at the other end of the machining unit to provide arotational force to the mandrel 40 to wind the coil spring material 2.Thus, compared to the prior art, an extra space can be formed at the oneend of the mandrel 40 so that the pair of the mandrels 40 are spacedapart at a short distance from a central portion of the body 20 tooppose each other at one end thereof.

Furthermore, the first cylinder 92 is disposed perpendicular to a lengthdirection of the mandrel 40 to provide a driving force for verticallymoving the chuck 90 which fixes the one end of the coil spring material2 to the one end of the mandrel 40. This further narrows a distancebetween the one end of one of the mandrels 40 and the one end of theother mandrel 40.

As a result, according to the invention, two coil spring materials 2produced from a furnace 1 are transported to the two mandrels 40,respectively which are spaced apart from each other at a short distanceand wound therearound, respectively, thereby producing two coil springs.

FIG. 5 is a plan view illustrating an apparatus for manufacturing a coilspring of FIG. 2. FIG. 6 is a side view illustrating guide roller partsin the apparatus for manufacturing the coil spring of FIG. 5. FIG. 7 isa plan view illustrating the guide roller parts of FIG. 6.

Referring to the drawings, the guide roller parts 60 each are disposedmovable along a length direction of the mandrel 40 to guide the coilspring material to be wound around the mandrel 40. Each of the guideroller parts 60 includes a guide roller 62, a second cylinder 64 and atransport part 70.

As shown in FIGS. 3 and 5, the guide roller 62 presses and guides thecoil spring material wound around the mandrel 40 toward the mandrel 40.The second cylinder 64 is disposed on an outer circumference of themandrel 40 to oppose each other, thereby moving the guide roller 62vertically.

That is, the guide roller 62 moves vertically by the second cylinder 64and is kept at a proper distance from the outer circumference of themandrel 40 so that the coil spring material 2 is located between themandrel 40 and the guide roller 62 in accordance with the outercircumference of the mandrel 40.

Preferably, the second cylinder 64 is configured with a controller (notillustrated) having Linear Variable Differential Transformer (LVDT) (64a of FIG. 6) which enables the guide roller 62 to be properly positionedto suit the outer circumference of the mandrel 40.

The transport part 70 includes a screw shaft 74 and a guide shaft 76.The screw shaft 74 rotates by a second motor 72 to transport the guideroller 62 along the length direction of the mandrel 40. The guide shaft76 guides the guide roller 62. Referring to FIG. 5, the second motor 72shown in the one end of the mandrel 40 is connected to a timing belt 72a to rotate the screw shaft 74 of the guide roller 60 disposed in alower part of the mandrel 40.

On the screw shaft, a screw housing 74 a is configured movable alongwith rotation of the screw shaft 74. On the guide shaft 76, a guidehousing 76 a is disposed movable along the guide shaft 76. Preferably,the screw housing 74 a and the guide housing 76 a each have a ball in aninner circumference thereof to move the screw shaft 74 and the guideshaft 76 smoothly. Also, preferably, the guide shaft 76 is constructedof a spline shaft to ensure both ends thereof to be fastened to the body20.

Moreover, the guide roller part 60 further includes a third cylinder 80configured to reciprocally move the guide roller 62 along the guideshaft 76 to vary a lead angle of the coil spring material while theguide roller moves along the screw shaft 74.

The third cylinder 80 is fixed to the screw housing 74 a to reciprocallymove the guide roller 62 disposed in the guide housing 76 a along theguide shaft 76 with respect to the screw housing 74 a. That is, tomanufacture the coil spring with irregular pitches due to a variablelead angle, the third cylinder 80 is configured such that the guideroller 62 moves back and forth with respect to a moving direction whilethe guide roller 62 moves along the screw shaft 74.

Preferably, the third cylinder 80 is configured with a controller (notillustrated) having the LVDT (80 a of FIG. 7) to control the variablelead angle.

Moreover, as shown in FIG. 3, the apparatus for manufacturing the coilspring, a pair of the guide roller 60 is disposed at both sides of themandrel 40 to selectively produce a left- or right-handed coil spring.Here, the guide roller parts 60 can be installed above the mandrels 40as shown or below the mandrels 40.

That is, in the apparatus for manufacturing the coil spring, the twomandrels 40 are disposed co-planar in a central portion of the body 20to oppose each other at one end thereof. Also, each of the mandrel 40 isconstructed of the guide roller part 60 to selectively produce the left-or right-handed coil spring.

Meanwhile, as shown in FIGS. 3 and 5, the body 20 is configured as anupper body 20 a and a lower body 20 b with respect to hinges 30 formedrespectively below the one end of the mandrel 40.

Here, the mandrels 40, the first motors, and the guide rollers 60 aredisposed in the upper body 20 a. Third motors 22 are disposed in thelower body 20 b to rotate the upper body 20 a about the hinges 30.

With rotation of the screw shaft 22 a, which drives the third motors 22,the upper body 20 a joined to the screw shaft 22 a also moves.Preferably, each of the third motors 22 is configured with a decelerator22 b which decelerates at an adequate ratio to achieve a high torque.

Here, a moving roller 32 is disposed on an underside surface of the body20 a and a curve rail 34 is formed on an upper surface of the lower body20 b. Accordingly, when the moving roller 32 moves along the curve rail34 by the third motor 22, the upper body 20 a rotates about the hinges30.

Conventionally, the coil spring material 2 was wound with the one endthereof fixed by gradually increasing a lead angle thereof. That is,there was no initial lead angle. However, the body 20 configured as justdescribed is rotatable about the hinges 30, thereby producing the coilspring with the initial lead angle.

That is, the mandrel 40 rotates when the upper body 20 a rotates at acertain angle as described above. This enables the coil spring material2 to have the initial lead angle formed at the one end thereof.

As shown in FIG. 3, in the apparatus for manufacturing the coil spring,each of the machining units further includes a tangent roller 98 spacedapart at a predetermined distance from the outer circumference of themandrel 40 to separate the other end of the coil spring material formthe mandrel 40.

The tangent roller 98 is placed at a predetermined distance from theouter circumference of the mandrel 40 to guide the moving coil springmaterial, thereby separating the other end of the coil spring from themandrel 40 at a predetermined distance.

That is because the coil spring produced from the coil spring material 2has the other end fixed to a body (not illustrated) of a car. That is,in a case where the other end of the coil spring is round, the coilspring idles with respect to the body of the car. To prevent this, theother end of the coil spring is spaced apart from the mandrel at apredetermined distance 40. Accordingly, the edge portion of the otherend of the coil spring is hooked onto a hook (not illustrated) formed inthe car.

Now, a detailed explanation will be given about a method formanufacturing a coil spring with an apparatus for manufacturing a coilspring according to a preferred embodiment of the invention.

First, each of two coil spring materials 2 produced from a furnace 1 istransported to one end of each of two mandrels 40 which are disposedcoplanar and opposing each other at one end thereof.

Then, the one end of the coil spring material 2 is pressed toward andfixed to the mandrel 40 by a chuck 90 disposed at the one end of themandrel 40.

That is, the chuck 90 disposed in a mandrel fixing part 42 presses theone end of the coil spring material 2 toward the mandrel 40 by virtue ofa first cylinder 92 disposed at the one end of the mandrel perpendicularto a length direction of the mandrel. This allows the one end of thecoil spring material 2 to be fixed.

Next, a first motor 50 disposed at the other end of the mandrel 40 inthe body 20 is started to rotate the mandrel 40. With the mandrel 40rotating, the coil spring material 2 having one end fixed to the mandrel40 by a chuck 90 is wound around an outer circumference thereof.

Here, the guide roller 62 presses the coil spring material 2 woundaround the mandrel 40 toward the mandrel 40 and guides the coil springmaterial 2 toward the other end of the mandrel 40. This allows the coilspring material 2 to be produced as a coil spring with a certain leadangle.

That is, a second motor 72 installed in the body 20 is set to motion torotate the screw shaft 74, thereby moving a guide roller 62 fixed to ascrew housing 74 a fastened to the screw shaft 74 in a length directionof the mandrel 40. This enables the coil spring material 2 to beproduced as the coil spring with a predetermined lead angle.

The guide roller 62 is moved vertically to guide the coil springmaterial 2 while pressing it against an outer circumference of themandrel 40. Here, such a vertical movement of the guide roller 62 isdriven by the second cylinder 64.

To vary a lead angle of the coil spring material 2 while the guideroller 62 moves along the screw shaft 74, the guide roller 62 movesreciprocally along the guide shaft 76 with respect to the screw housing74 a by the third cylinder 80.

Furthermore, to form an initial lead angle at the one end of the coilspring material 2, the third motor 22 disposed in a lower body 20 b isset to motion to rotate an upper body 20 a with respect to hinges 30.Then, when the mandrel 40 rotates with the upper body 20 a rotating at apredetermined angle, the coil spring material has the initial angleformed at the one end thereof.

Finally, to prevent the coil spring, when installed in a car body, fromidling, the other end of the coil spring material 2 is spaced apart fromthe mandrel 40 at a predetermined distance so that an edge portion ofthe other end of the coil spring is hooked onto a hook formed inside thecar body.

That is, the coil spring material 2 is guided to move toward a tangentroller 98 spaced apart from the outer circumference of the mandrel 40 ata predetermined distance so that the other end of the coil springmaterial 2 is spaced apart from the mandrel 40 at a predetermineddistance.

In the apparatus for manufacturing the coil spring as just described,one of two guide roller parts 60 disposed at both sides of the mandrel40 is selectively set to motion to produce a left- or right-handed coilspring, respectively from the two mandrels 40 at one time.

As set forth above, according to exemplary embodiments of the invention,an apparatus for manufacturing a coil spring has a pair of machiningunits disposed on a body. Each of the machining units has a first motordisposed at the other end of the machining unit to provide a drivingforce for rotating the mandrel in order to wind a coil spring material.Thus, compared with the prior art, an extra space is formed at one endof the mandrel so that the two mandrels are spaced apart at a shortdistance from a central portion of the body to oppose each other.

Also, a first cylinder is disposed perpendicular to a length directionof the mandrel to provide a driving force for vertically moving thechuck which fixes one end of the coil spring material to the one end ofthe mandrel. This further narrows a distance between the one end of oneof the mandrels and the one end of the other mandrel.

Consequently, according to the invention, two coil spring materialsproduced from a furnace are transported to the two mandrels spaced apartfrom each other at a short distance and wound therearound, respectivelyto produce two coil springs through a process.

One coil spring can be produced from the respective two mandrels at onetime. That is, according to the prior art, one coil spring is producedat one time while according to the invention, two coil springs areproduced at one time. Thus, given productivity of the coil springmanufactured from a furnace, the yield of the coil spring can beincreased on the basis of a predetermined manufacturing period.

Moreover, a guide roller part further includes a third cylinderconfigured to reciprocally move the guide roller along the guide shaft.Accordingly, the coil spring material can be varied in its lead anglewhile the guide roller moves along the screw shaft.

Also, according to the invention, a pair of the guide roller part isdisposed at both sides of the mandrel to selectively produce a left- orright-handed coil spring.

Meanwhile, the body is configured as an upper body and a lower body withrespect to hinges formed respectively below the mandrels. The mandrels,a first motor and the guide roller parts are disposed in the upper body.Also, third motors are disposed in the lower body to rotate the upperbody about the hinges.

That is, when the mandrels rotate with the upper body rotating at apredetermined angle as just described, the coil spring material has aninitial lead angle formed at one end thereof.

In addition, according to the invention, each of the machining unitsfurther includes a tangent roller spaced apart at a predetermineddistance from the outer circumference of the mandrel to guide the otherend of the moving coil spring material, thereby separating the other endof the coil spring material from the mandrels.

While the present invention has been shown and described in connectionwith the preferred embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

1. An apparatus for manufacturing a coil spring comprising: a body; apair of machining units disposed on the body to oppose each other at oneend thereof, wherein each of the machining units comprises; a mandreldisposed in an upper central part of the body, the mandrel rotatablyconfigured to wind a coil spring material around an outer circumferencethereof; a first motor disposed at the other end of the machining unitto provide a driving force for rotating the mandrel; and a guide rollerpart disposed movable along a length direction of the mandrel to guidethe coil spring material to be wound around the mandrel, wherein twocoil spring materials produced from a furnace are wound around themandrels, respectively to produce two coil springs through one process.2. The apparatus according to claim 1, wherein each of the machiningunits further comprises: a chuck configured vertically movable anddisposed at one end of the mandrel to fix one end of the coil springmaterial to the one end of the mandrel; and a first cylinder disposed atthe one end of the mandrel perpendicular to a length direction of themandrel to provide a driving force for moving the chuck vertically withrespect to the length direction of the mandrel.
 3. The apparatusaccording to claim 1, wherein each of the guide roller parts comprises:a guide roller for pressing and guiding the coil spring material woundaround the mandrel toward the mandrel; a second cylinder disposed at anouter circumference of the mandrel to oppose each other, thereby movingthe guide roller vertically; and a transport part having a screw shaftrotating by a second motor to transport the guide roller along thelength direction of the mandrel and a guide shaft for guiding the guideroller.
 4. The apparatus according to claim 3, wherein the guide rollerparts further comprises a third cylinder configured to reciprocally movethe guide roller along the guide shaft to vary a lead angle of the coilspring material while the guide roller moves along the screw shaft. 5.The apparatus according to claim 4, wherein a pair of the guide rollerpart is disposed at both sides of the mandrel to selectively produce aleft- or right-handed coil spring.
 6. The apparatus according to claim1, wherein the body is configured as an upper body and a lower body withrespect to hinges formed respectively below the mandrels, wherein themandrels, the first motors, and the guide roller parts are disposed inthe upper body, the apparatus further comprising third motors disposedin the lower body to rotate the upper body about the hinges.
 7. Theapparatus according to claim 1, wherein each of the machining unitsfurther comprises a tangent roller spaced apart at a predetermineddistance from the outer circumference of the mandrel to separate theother end of the coil spring material from the mandrels, thereby guidingthe other end of the moving coil spring material.
 8. The apparatusaccording to claim 2, wherein each of the machining units furthercomprises a tangent roller spaced apart at a predetermined distance fromthe outer circumference of the mandrel to separate the other end of thecoil spring material from the mandrels, thereby guiding the other end ofthe moving coil spring material.
 9. The apparatus according to claim 3,wherein each of the machining units further comprises a tangent rollerspaced apart at a predetermined distance from the outer circumference ofthe mandrel to separate the other end of the coil spring material fromthe mandrels, thereby guiding the other end of the moving coil springmaterial.
 10. The apparatus according to claim 6, wherein each of themachining units further comprises a tangent roller spaced apart at apredetermined distance from the outer circumference of the mandrel toseparate the other end of the coil spring material from the mandrels,thereby guiding the other end of the moving coil spring material.